1. Field of the Invention
The present invention relates to a wireless communication apparatus. In particular, the present invention relates to a semiconductor device in which transmitter and receiver circuits are integrated on a semiconductor chip, and to a wireless communication apparatus using the same.
2. Description of the Related Art
In a wireless communication apparatus used for a cellular phone and the like, a transmitting unit and a receiving unit are installed in a chassis or phone housing. In the receiving unit of the wireless communication apparatus, electrical characteristics deteriorate due to electromagnetic disturbances caused by spurious signals entering from the transmitting unit of the wireless communication apparatus, interference waves from other wireless communication apparatuses, and the like. The closest source of electromagnetic disturbance for the receiving unit is the transmitting unit in the same chasis. For example, in a wireless communication apparatus using a time division duplex (TDD) mode such as the personal handyphone system (PHS) which is served in Japan, China, and some Asian countries, timing between transmission and reception differs from each other. Therefore, even when installing a transmitting unit and a receiving unit in the same shield, spurious signals are not generated because operation of the transmitting unit can be suspended during reception. However, in communication methods defined by Interim Standard-95 (IS-95), which is one of the standards for a cellular phone system using code division multiple access (CDMA), and as defined by the 3rd Generation Partnership Project (3GPP), transmitting and receiving units simultaneously operate. Thus, in a wireless communication apparatus used for a communication system in which transmitting and receiving units simultaneously operate, part of transmitting radio frequency (RF) output signals, or spurious signals and the like may create an electromagnetic disturbance to the receiving unit, and cause problems including the deterioration of reception sensitivity. Therefore, in a wireless communication apparatus, in order to prevent the deterioration of electrical characteristics of a receiving unit, each of transmitting and receiving units needs a grounded shield. In a current wireless communication apparatus, parts for the transmitting and receiving units can be positioned so as to be separated from each other. Accordingly, each of transmitting and receiving units can be independently shielded. Moreover, since sufficient electrical isolation between the transmitting and receiving units can be provided by grounded shields, a transmitter signal entering from the transmitting unit to the receiving unit can be suppressed.
However, advances in integrated circuits (ICs) for transmitting and receiving units based on the demand for miniaturization of a wireless communication apparatus has developed a semiconductor device which is monolithically integrated on a single chip which has a part of transmitter and receiver circuits encapsulated in a package. In a wireless communication apparatus using such a semiconductor device, shielding against interference waves from external wireless communication apparatuses is possible. However, it is difficult to provide shielding so as to completely isolate the transmitting and receiving units. Therefore, the electromagnetic disturbance by undesired signals which are transmitting spurious and its transmitting signal entering from the transmitting unit to the receiving unit deteriorates the receiving characteristics of the wireless communication apparatus. Moreover, in a semiconductor chip of the transceiver monolithic IC, signals leaked in the receiving side from the transmitting side also deteriorate characteristics of the receiving circuit.